package com.wc.alorithm_blue_bridge_history.littlewhite.Q231209.Q9497;

import java.util.Scanner;

/**
 * @Author congege
 * @Description
 * @Date Created in 2023/12/9-19:23
 */
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] a = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            a[i] = sc.nextInt();
        }
        int ans = 0;
        for (int i = 2; i < n; i++) {
            if (a[i] >= a[i - 1] + a[i + 1]){
                ans++;
            }
        }
        System.out.println(ans);
    }
}
